Patent Application
20240280548
The present invention relates to a method and a device for screening a sample containing phenol, isopropylated phosphate.
Phenol, isopropylated phosphate (3:1) (PIP (3:1), CAS: 68937-41-7) is widely used as additives for imparting flame retardancy and plasticity to resin products such as poly vinyl chloride (PVC). In addition, PIP (3:1) also has abrasion resistance and pressure resistance, and thus is widely used as an additive for a hydraulic fluid, an adhesive, and the like. In Non Patent Literature 1 issued by the Environmental Protection Agency (EPA) of the United States, PIP (3:1) is defined as a group of compounds having a molecular structure in which triphenyl phosphate is a basic structure and all three phenyl groups have one or more isopropyl groups as substituents.
The EPA has certified PIP (3:1) as one of the substances having persistent, bioaccumulative, and toxic properties (PBT), based on the Toxic Substances Control Act (TSCA) of the United States (Non Patent Literature 2). Accordingly, export of products containing PIP (3:1) to the United States is restricted. In order to comply with this regulation, it is necessary to confirm previously that products to be exported to the United States do not contain PIP (3:1).
Non Patent Literatures 3 and 4 state that a sample solution in which a sample is dissolved is analyzed using LC/MS or GC/MS, and the amount of PIP (3:1) contained in the sample can be measured. In addition, Non Patent Literature 5 states that PIP (3:1) contained in the sample can be measured by using Py/TD-GC/MS which is a combination of Py/TD and the gas chromatography mass spectrometry, where Py/TD is a method of thermally desorbing (TD) components such as PIP (3:1) contained in a sample by a pyrolyzer (Py) which heats the sample as it is.
PIP (3:1) includes a large number of compounds having different numbers of substitutions or different substitution positions of the isopropyl group of the phenyl group, but when mass spectrometry is used as in Non Patent Literatures 3 to 5, a group of compounds having the same number of substitutions of the isopropyl group are detected as ions having one common mass-to-charge ratio, whereby the group of compounds can be measured at a time. However, since the composition ratio of compound groups with each substitution number differs due to differences in manufacturing conditions and other factors, it may be difficult to detect a compound group of a substitution number with low composition ratio. Even if the constituent ratio is the same, because the measurement sensitivity of compound groups having each number of substitutions is also different, a compound group of a substitution number having considerable composition ratio may be sometimes difficult to detect. Therefore, it is difficult to determine that the sample contains PIP (3:1) based on the detection of all the compound groups corresponding to PIP (3:1).
In order to simplify the measurement, it is possible to measure only a part of all the compound groups having different numbers of substituents. However, as described above, the composition ratio (concentration) of each compound group in the product varies depending on the production conditions, and the measurement sensitivity of each compound group also varies, and thus it is difficult to determine which compound group should be set as the measurement target when screening a sample of a product or the like containing PIP (3:1). For example, when the content of the compound group to be measured is low or the measurement sensitivity is low, it was possible to miss the presence of PIP (3:1) in the sample. In addition, in a case where only one type of the compound group is to be measured, when ions of a foreign substance having the same mass-to-charge ratio as that of the compound group are present, it was possible to misidentify the content of the foreign substance as the content of the compound group and erroneously determine the presence of PIP (3:1) even though it is not actually contained.
An object of the present invention is to provide a screening technique capable of easily and correctly determining whether a sample to be analyzed contains phenol, isopropylated phosphate (3:1).
A method for screening a sample containing phenol, isopropylated phosphate (3:1) according to the present invention made in order to solve the above problems includes:
A device for screening a sample containing phenol, isopropylated phosphate (3:1) according to the present invention made in order to solve the above problems includes:
Phenol, isopropylated phosphate (3:1) (PIP (3:1)), which is the compound to be screened in the present invention, is a compound group in which x, y and z in the above chemical formula 1 are all 1 or more. Examples of the compound group represented by the above chemical formula 1 include compounds in which x, y, and z each have a value from 0 to 5. During the production of the product containing PIP (3:1), not only PIP (3:1) but also a compound in which any phenyl group does not have an isopropyl group (R in the above chemical formula) is produced simultaneously as a by-product. In addition, for the product containing PIP (3:1), a compound having a smaller number of substitutions of the isopropyl group is contained more. The present invention has been made based on these findings obtained by the inventors of the present invention.
The present invention acquires, as a measured value, the content or a value corresponding to the content of a plurality of the compound groups, having triphenyl phosphate as the basic structure like PIP (3:1), among a compound group in which the total number of isopropyl groups that three phenyl groups have as substituents is 1, a compound group in which the total number is 2, and a compound group in which the total number is 3. The compound group having a small number of substitutions of isopropyl groups, which is the target compound in the present invention, is contained in a large amount in a sample of a product or the like containing PIP (3:1), and thus a correct measured value can be obtained. Therefore, whether or not the sample to be analyzed contains PIP (3:1) is correctly determined by comparing the measured value of each target compound with a predetermined threshold. The threshold may be a different value or the same value for each compound group. In addition, it is rare that foreign substances having the same mass-to-charge ratio for a plurality of target compounds are simultaneously present in one sample, and thus it is possible to prevent erroneous determination by measuring a plurality of compound groups as in the present invention. Further, screening can be performed more easily than measuring all the compound groups having different numbers of substituents.
Embodiments of a method and a device for screening a sample containing phenol, isopropylated phosphate (3:1) (PIP (3:1), CAS: 68937-41-7) according to the present invention will be described below with reference to the drawings.
In the present embodiment, a pyrolyzer/thermal desorption device-gas chromatograph mass spectrometer (Py/TD-GC/MS) 1 is used to screen samples to be analyzed and possibly having PIP (3:1). The sample to be analyzed in the present embodiment is, for example, a resin product, a hydraulic fluid, or an adhesive. PIP (3:1) is defined in Non Patent Literature 1 as a compound group in which x, y, and z are all 1 or more among compounds represented by the following chemical formula 1 (x, y, and z are the number of isopropyl groups each phenyl group has as a substituent).
The Py/TD-GC/MS1 roughly includes a gas chromatograph (GC) unit 10, a mass spectrometer (MS) unit 20, and a control/processing unit 30. The gas chromatograph unit 10 includes a sample vaporizing chamber 11, a pyrolyzer (Py) 12, a carrier gas flow path 13 connected to the sample vaporizing chamber 11, and a column 14 connected to an outlet of the sample vaporizing chamber 11. The pyrolyzer 12 can also be used as a thermal desorption device (TD) by changing its heating temperature. The column 14 is accommodated in a column oven 15. Each of the pyrolyzer 12 and the column 14 in the column oven 15 is heated to a predetermined temperature by a heating mechanism (not illustrated).
The mass spectrometer unit 20 includes an electron ionization source 22, an ion lens 23, a quadrupole mass filter 24, and an ion detector 25 in a vacuum chamber 21. Sample components temporally separated in the column 14 are sequentially introduced into the electron ionization source 22, and ionized by irradiation of thermoelectrons emitted from a filament (not illustrated).
The control processing unit 30 includes a storage unit 31. The storage unit 31 stores a method file in which sample measurement conditions are described. The measurement conditions described in the method file include the temperature of the pyrolyzer 12, the temperature of the column 14, the type and flow rate of the carrier gas, the range of the mass-to-charge ratio to be measured in the scan measurement, the retention time of each compound included in the plurality of compound groups (compound groups 1 to 3), information on the mass-to-charge ratio (monitoring m/z) of the ion to be measured (target ion) for each compound group, and the like.
The control/processing unit 30 includes, as functional blocks, a standard sample measurement unit 32, a calibration curve creation unit 33, an actual sample measurement unit 34, a measurement value acquisition unit 35, a determination unit 36, and an information output unit 37. An entity of the control/processing unit 30 is a general personal computer, and these functional blocks are embodied by executing a screening program installed previously by a processor. An input unit 4 for a user to perform an input operation and a display unit 5 for displaying various types of information are connected to the control/processing unit 30.
Next, a procedure of screening using Py/TD-GC/MS1 of the present embodiment will be described with reference to a flowchart in
In the present embodiment, a standard sample is measured before screening of an actual sample (step 1). The standard sample used in the present embodiment is a resin sample containing a known amount of a plurality of compound groups represented by the above chemical formula 1 (x, y, and z each represent the number of isopropyl groups that the phenyl group has as a substituent, a compound group in which the total of x, y, and z is 1 to 3 is included). The measurement of the standard sample only needs to be performed once, and the measurement of the standard sample can be omitted by storing the calibration curve created based on the result in the storage unit 31. In the present embodiment, the resin sample is used as the standard sample, but the type of the standard sample may be appropriately selected according to the type of the sample to be measured (typically, the same type of sample as the sample to be measured is selected).
When a user sets a standard sample in the pyrolyzer 12 and instructs measurement of the standard sample, the standard sample measurement unit 32 reads a method file (refer to
The ions generated by the electron ionization source 22 are converged in the vicinity of the central axis (ion optical axis C) in the flight direction by the ion lens 23, then incident on the quadrupole mass filter 24, separated according to the mass-to-charge ratio, and detected by the ion detector 25. The output signals from the ion detector 25 are sequentially transmitted to and stored in the storage unit 31.
During the measurement of the standard sample, the mass spectrometer unit 20 repeatedly performs scan measurement and selected ion monitoring (SIM) measurement. Specifically, a scan measurement in which the mass-to-charge ratio of ions passing through the quadrupole mass filter 24 is scanned in a predetermined range (m/z is 50 to 1000 in the present embodiment) and SIM measurement in which the mass-to-charge ratio of ions passing through the quadrupole mass filter 24 is fixed to the mass-to-charge ratio of target ions of each compound group for a predetermined time are set as one set, and these are repeatedly performed. In the present embodiment, a target ion (ion having monitoring m/z) is subjected to SIM measurement for each of a compound group having one substituent (compound group 1), a compound group having two substituents (compound group 2), and a compound group having three substituents (compound group 3). Therefore, in the present embodiment, one scan measurement and three types of SIM measurement constitute one set.
When the measurement of the standard sample is completed, the calibration curve creation unit 33 reads the output signal of the ion detector 25 stored in the storage unit 31. Then, a total ion current chromatogram is created using the output signal obtained at the time of scan measurement. In addition, a mass chromatogram of each of the compound groups 1 to 3 is created using the output signals obtained at the time of the three SIM measurements. The compound groups 1 to 3 include a plurality of compounds having different substitution positions of the isopropyl group, and thus a plurality of mass peaks typically appear in each mass chromatogram. In the present embodiment, a calibration curve of each of the compound groups 1 to 3 is created based on the total of peak areas (or peak heights) of a plurality of mass peaks appearing on the mass chromatogram of one compound group, and the amount of the compound groups 1 to 3 contained in the standard sample (
In the present embodiment, information on the retention time of the compound contained in each of the compound groups 1 to 3 is described previously in the method file stored in the storage unit 31 (the retention time is known), but when the retention time is unknown, a retention index may be used. When the retention index is used, the n-alkane sample is measured separately from the measurement of the standard sample. The n-alkane sample is a standard sample containing a plurality of compounds having different lengths of hydrocarbon chains, and is used to obtain a retention index based on the retention time of each compound. The retention index Ix of a compound x is represented by the following formula (1).
Herein, Cn and Cn+i are the numbers of carbon atoms in the n-alkane whose retention times are located before and after the retention time of the compound, tx is the retention time of the compound x, and tn and tn+i are the retention times of the n-alkane whose retention times are located before and after the retention time of the compound.
Thereafter, when the user inputs information on the sample to be analyzed (sample name and the number of samples), sets the first sample in the pyrolyzer 12, and instructs start of measurement, the actual sample measurement unit 34 reads the method file (refer to
When the measurement of the actual sample is completed, the measurement value acquisition unit 35 reads the output signal of the ion detector 25 stored in the storage unit 31, and creates a total ion current chromatogram and a mass chromatogram corresponding to each of the compound groups 1 to 3, similarly to the measurement of the standard sample. Then, the area (or peak height) of a mass peak of each compound belonging to the compound group on the mass chromatogram of each of the compound groups 1 to 3 is determined, and the sum thereof is calculated. Then, the content of each of the compound groups 1 to 3 is obtained based on the calibration curve stored in the storage unit 31 (step 4).
When the content of the compound groups 1 to 3 is acquired, the determination unit 36 calculates the concentration of each of the compound groups 1 to 3 from the weight of the sample to be analyzed (the weight of the sample set in the pyrolyzer 12) and the content. Subsequently, the thresholds L1 to L3 associated with the respective compound groups 1 to 3 are read and compared (step 5, refer to
When the number of compound groups having a concentration exceeding the threshold is 0 or 1 (NO in step 6), the determination unit 36 determines that there is a high possibility that the sample does not contain PIP (3:1). Meanwhile, when the concentrations of the plurality of compound groups exceed the threshold (YES in step 6, refer to
When the above processing by the determination unit 36 and the information output unit 37 is completed, the actual sample measurement unit 34 confirms the presence or absence of an unmeasured sample, and when there is an unmeasured sample (YES in step 8), the process returns to step 3 and repeats the same processing as described above. When there is no unmeasured sample (NO in step 8), the series of processing is ended.
As described above, in the present embodiment, in order to determine whether or not the sample to be analyzed contains PIP (3:1), a group of compounds having a basic structure common to PIP (3:1) and having the number of substitutions of the isopropyl group of 1 to 3 is measured. This is based on the fact that, as a result of measuring various samples containing PIP (3:1), the inventors of the present invention have found that samples containing PIP (3:1) contain not only PIP (3:1) but also compounds in which any phenyl group does not have an isopropyl group R as a by-product, and in many cases, their contents are higher than PIP (3:1).
In addition, as a result of mass spectrometry of a compound group having different numbers of substituents, it has been also found that the measurement sensitivity tends to be higher as the number of substituents is smaller. Therefore, as in the present embodiment, using the concentration of the compound groups 1 to 3, which is contained in a large amount in a sample containing PIP (3:1) and has high measurement sensitivity, as a criterion of determination can completely screen a sample containing PIP (3:1).
During the production of the product containing PIP (3:1), not only PIP (3:1) but also a compound in which any phenyl group does not have an isopropyl group (R in the above chemical formula 1) is produced simultaneously as a by-product. It is not easy to selectively remove such by-product, or selectively extract only PIP (3:1), or produce only PIP (3:1) so that no by-products are generated, and thus products containing PIP (3:1) contain such by-products with a high probability. Therefore, it can be said that instead of directly measuring PIP (3:1), determining that PIP (3:1) is contained based on the fact that the compound groups 0 to 3 generated as by-products of PIP (3:1) are contained is appropriate as a determination method.
In the above embodiment, the concentration of the compound groups 1 to 3 is compared with the threshold, but only two of the compound groups 1 to 3 may be measured. In a case where there is a foreign substance that generates an ion having the monitoring ml set for the compound group, measurement of only one of the compound groups arises a possibility that it is erroneously determined that the compound group is measured although the foreign substance is detected, and determination of screening becomes erroneous. Therefore, it is preferable to compare the concentrations of the plurality of compound groups with the threshold. In addition, in the above embodiment, the concentration of each of the compound groups is obtained and compared with the threshold, but if the weight of the sample to be measured is constant, the threshold of the content may be set.
The above-described embodiment is merely an example, and can be modified as appropriate in accordance with the spirit of the present invention. Some modifications will be described below.
In the above embodiment, the concentrations of a plurality of compound groups of the compound groups 1 to 3 in the sample to be analyzed were compared with the threshold, but as shown in
In the above embodiment, a threshold is set for each of the compound groups 1 to 3, and the sample is screened based on the result of comparing the concentration of the compound groups 1 to 3 contained in the sample to be analyzed with each threshold. However, in addition to this, a threshold (total threshold) may be set for the total concentration of the compound groups (for example, the compound groups 1 to 3) to be measured, and the sample may be screened in consideration of the result of comparing the total concentration of a plurality of compound groups obtained by measurement with the threshold.
In PIP (3:1), the ratio of the content of the compound groups for each number of substitutions of the isopropyl group may vary depending on the production conditions and the like, and thus the concentration of a specific compound group may be low. In addition, ionization of a specific compound group is suppressed (ion suppression) due to the influence of other components contained in the sample, and the measurement sensitivity may be lowered. Even in these cases, in the second modification, the possibility of missing presence of PIP (3:1) in the sample can be reduced by comparing the sum with the measured values of other compound groups with the threshold.
In the above embodiment, the content of each of the compound groups is determined from the peak area (or peak height) of the mass chromatogram, and the concentration of each of the compound groups is determined based on the content and the weight of the sample. However, as in the above embodiment, when the device for measuring a standard sample and the device for measuring a sample to be analyzed are the same or of the same type and the measurement conditions are substantially the same, the peak area or the peak height may be compared with the threshold.
PIP (3:1) is a collection of many compounds, and thus the content and concentration of each of the compounds may not be accurately known even for a standard sample. In the third modification, even in such a case, using the measurement result of the standard sample or the like as a reference and using its peak area or peak height as a threshold can provide screen determination based on whether or not the compound group to be measured is contained at a higher concentration than the standard sample.
In the above embodiment and modifications, the configuration in which a sample containing PIP (3:1) is screened by measurement using Py/TD-GC/MS has been described. However, other measurement methods can be used as long as the compound group can be measured as in the above embodiment and modifications. For example, it is possible to adopt a configuration in which chromatography (gas chromatography, liquid chromatography, or the like that detects each compound by spectroscopic measurement or the like) using only a chromatograph is performed, and each compound separated in the column is measured. However, using the mass spectrometry as described above can measure a plurality of compounds having the same number of substitutions by one common monitoring m/z, and thus it is preferable to use the mass spectrometry. In addition, when Py/TD is used, pretreatment such as dissolving a sample in a solvent is unnecessary, and thus Py/TD is preferably used. In addition, mass spectrometry (TD-MS) or the like not using chromatographic separation may be used.
It is understood by those skilled in the art that the plurality of exemplary embodiments described above are specific examples of the following modes.
A method for screening a sample containing phenol, isopropylated phosphate (3:1) according to one mode of the present invention includes:
A device for screening a sample containing phenol, isopropylated phosphate (3:1) according to another mode of the present invention includes:
Phenol, isopropylated phosphate (3:1) (PIP (3:1)), which is the compound to be screened in the screening method of Clause 1 and the screening device of Clause 6, is a compound group in which x, y and z in the above chemical formula 1 are all 1 or more. During the production of the product containing PIP (3:1), not only PIP (3:1) but also a compound in which any phenyl group does not have an isopropyl group (R in the above chemical formula 1) is produced simultaneously as a by-product. In addition, for the product containing PIP (3:1), a compound having a smaller number of substitutions of the isopropyl group contains more PIP.
The screening method of Clause 1 and the screening device of Clause 6 acquire, as a measured value, the content or a value corresponding to the content of a plurality of the compound groups, having triphenyl phosphate as the basic structure like PIP (3:1), among a compound group in which the total number of isopropyl groups that three phenyl groups have as substituents is 1, a compound group in which the total number is 2, and a compound group in which the total number is 3. The compound group having a small number of substitutions of the isopropyl group, which is the target compound in the screening method of Clause 1 and the screening device of Clause 6, is contained in a large amount in a sample of a product or the like containing PIP (3:1), and thus the content of PIP (3:1) can be completely determined. Whether or not the sample to be analyzed contains PIP (3:1) can be correctly determined by comparing the measured value of each target compound with a predetermined threshold. The threshold may be a different value or the same value for each compound group. In addition, it is rare that foreign substances having the same mass-to-charge ratio for a plurality of target compounds are simultaneously present in one sample, and thus it is possible to prevent erroneous determination by measuring a plurality of compound groups as in the screening method of Clause 1 and the screening device of Clause 6. Further, screening can be performed more easily than measuring all the compound groups having different numbers of substituents.
In the method for screening a sample containing phenol, isopropylated phosphate (3:1) according to Clause 1,
In the screening method of Clause 2, triphenyl phosphate (compound having 0 substituent) and a compound group having 4 or more substituents are further subjected to measurement, and the measured values of more compound groups are compared with the threshold, so that the sample containing phenol, isopropylated phosphate (3:1) can be screened with higher accuracy.
In the method for screening a sample containing phenol, isopropylated phosphate (3:1) according to Clause 1 or 2,
In the screening method of Clause 3, the sample containing phenol, isopropylated phosphate (3:1) is screened based on a result of comparing not only the measured value for each of the compound groups but also the total of the measured values of the plurality of compound groups with a predetermined threshold. At the time of producing a product or the like containing PIP (3:1), there is a possibility that the proportion of the content of each of the compound groups changes depending on production conditions, and each of the compound groups is contained in a distribution different from the proportion assumed at the time of setting the threshold. In addition, even if each of the compound groups is contained at an assumed proportion, ionization of a specific compound group may be suppressed by other components contained in the sample (ion suppression). In the screening method of Clause 3, the threshold is compared not only for each of the compound groups, but also whether or not PIP (3:1) is contained is determined based on the result of comparing the total of the measured values of other compound groups with the threshold, so that the possibility of overlooking PIP (3:1) contained can be reduced.
In the method for screening a sample containing phenol, isopropylated phosphate (3:1) according to any one of Clauses 1 to 3,
In the screening method of Clause 4, the screening of the sample containing phenol, isopropylated phosphate (3:1) can be more easily performed without a step of determining the content itself of the compound group.
In the method for screening a sample containing phenol, isopropylated phosphate (3:1) according to any one of Clauses 1 to 4,
In the screening method of Clause 5, when only the measured values of some of the compound groups exceed the threshold, information prompting confirmation of the sample is output, so that the possibility of overlooking the sample containing phenol, isopropylated phosphate (3:1) can be reduced with higher accuracy.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/030949 | 8/24/2021 | WO |
